The State of Web Vitals

Unused CSS bytes on Wix sites

11.1% of audited sites (625) parse over 600 KB of unused CSS rules before first paint, passing LCP at 89% (1.4s median) compared with 96% (1.0s median) under 140 KB.

Field data PhoneDesktopAll Scope All sites October 2026 edition · Phone field outcomes · Wix sites only
Wix Scoped to 5,623 sites out of 203,892 analyzed (cms) Compare with all sites →

33.8% of Wix sites use under 140 KB of unused CSS unused CSS bytes, and 96% of those sites have a good LCP, against 94% of all Wix sites.

The State of Web Vitals · October 2026 · Wix: 5,621 crawled sites · 3,077 with phone field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
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LCP pass rate

Sites with under 140 KB of unused CSS unused CSS bytes have a good LCP most often: 96%, against 94% of all Wix sites. Sites with over 600 KB of unused CSS unused CSS have it least often, at 89%.

SitesGood, needs improvement, poor LCPMedian
All Wix sites3,07794%1.1s
Under 140 KB unused 33.8%1,04996%997ms
140 to 300 KB unused 31.0%95196%1.1s
300 to 600 KB unused 24.1%72391%1.3s
Over 600 KB unused 11.1%35489%1.4s
GoodNeeds improvementPoorSites: with Chrome field data
The State of Web Vitals · October 2026 · Wix: 5,621 crawled sites · 3,077 with phone field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
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Unused CSS bytes usage

Under 140 KB of unused CSS is the most used: 33.8% of Wix sites.

Under 140 KB unused 33.8% 140 to 300 KB unused 31.0% 300 to 600 KB unused 24.1% Over 600 KB unused 11.1%
Under 140 KB unused 33.8% 140 to 300 KB unused 31.0% 300 to 600 KB unused 24.1% Over 600 KB unused 11.1%
The State of Web Vitals · October 2026 · Wix: 5,621 crawled sites · 3,077 with phone field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
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The four LCP phases

Across the four LCP sub-parts in Chrome's field data, the largest gap between under 140 KB of unused CSS and over 600 KB of unused CSS sits in resource load delay: 390 ms median for under 140 KB of unused CSS against 528 ms for over 600 KB of unused CSS. Overall median field LCP is 1.0s for under 140 KB of unused CSS (TTFB 380 ms, load delay 390 ms, load duration 102 ms, render delay 155 ms) versus 1.4s for over 600 KB of unused CSS.

Median LCP phase breakdown (Chrome field p75) Load delay Median LCP
All Wix sites 2,353404 ms446 ms150 ms446 mslab 453 ms1.1s
Under 140 KB unused 794380 ms390 ms155 ms390 mslab 403 ms1.0s
140 to 300 KB unused 736403 ms437 ms147 ms437 mslab 443 ms1.1s
300 to 600 KB unused 554438 ms493 ms147 ms493 mslab 499 ms1.3s
Over 600 KB unused 269437 ms528 ms145 ms528 mslab 549 ms1.4s
TTFB Resource load delay Resource load time Element render delay
The State of Web Vitals · October 2026 · Wix: 5,621 crawled sites · 3,077 with phone field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
4

Unused CSS bytes per framework

On React, 34% of sites use under 140 KB of unused CSS unused CSS bytes, and 94% of React sites have a good LCP, against 94% of all sites.

FrameworkUnused CSS bytes on its sitesGood LCP
All Wix sites 5,621 sitesUnder 140 KB unused 34%140 to 300 KB unused 31%300 to 600 KB unused 24%Over 600 KB unused 11%94%
React 5,620 sitesUnder 140 KB unused 34%140 to 300 KB unused 31%300 to 600 KB unused 24%Over 600 KB unused 11%94%
Under 140 KB unused 140 to 300 KB unused 300 to 600 KB unused Over 600 KB unused
The State of Web Vitals · October 2026 · Wix: 5,621 crawled sites · 3,077 with phone field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
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Unused CSS bytes or the framework

Does the framework explain the unused CSS bytes difference?

On React, 96% of sites with under 140 KB of unused CSS unused CSS bytes have a good LCP, against 96% of React sites with 140 to 300 KB of unused CSS. Within React, sites with under 140 KB of unused CSS and 140 to 300 KB of unused CSS have a good LCP about equally often.

Why unused CSS slows both network transfer and style calculation

Browsers must match every selector in the CSSOM against the DOM tree during layout and style recalculation. Across 1,901 sites (33.8%) with under 140 KB of unused CSS, 96% pass field LCP at a 1.0s median, whereas the 11.1% (625) over 600 KB drop to 89% good LCP (1.4s median).

The State of Web Vitals · October 2026 · Wix: 5,621 crawled sites · 3,077 with phone field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
6

Understanding unused CSS bytes

Compile per-template CSS or run PurgeCSS/Tailwind content scanning so pages do not block first paint on hundreds of kilobytes of unreferenced selectors. Across all audited sites, 33.8% stay under 140 KB of unused CSS (96% good LCP, 1.0s median) versus 11.1% above 600 KB (89% good LCP, 1.4s median).

Go fix it Remove unused CSS → Eliminate render-blocking resources →
The State of Web Vitals · October 2026 · Wix: 5,621 crawled sites · 3,077 with phone field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
Related signals Iframes per page → Image fetchpriority → Responsive image markup → Script coverage (used vs unused) → By Arjen Karel · 5,621 crawled Wix sites (3,077 with phone Chrome field data, October 2026) · How we measured